content: /**
   * Copyright (c) 2016-present, RxJava Contributors.
   *
   * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in
   * compliance with the License. You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software distributed under the License is
   * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See
   * the License for the specific language governing permissions and limitations under the License.
   */
  package io.reactivex.observable.observers;
  
  import java.util.concurrent.atomic.AtomicReference;
  
  import io.reactivex.common.*;
  import io.reactivex.common.functions.Consumer;
  import io.reactivex.common.internal.disposables.DisposableHelper;
  import io.reactivex.common.internal.utils.ExceptionHelper;
  import io.reactivex.observable.*;
  import io.reactivex.observable.extensions.QueueDisposable;
  
  /**
   * An Observer that records events and allows making assertions about them.
   *
   * <p>You can override the onSubscribe, onNext, onError, onComplete, onSuccess and
   * cancel methods but not the others (this is by design).
   *
   * <p>The TestObserver implements Disposable for convenience where dispose calls cancel.
   *
   * @param <T> the value type
   */
  public class TestObserver<T>
  extends TestConsumer<T, TestObserver<T>>
  implements Observer<T>, Disposable, MaybeObserver<T>, SingleObserver<T>, CompletableObserver {
      /** The actual observer to forward events to. */
      private final Observer<? super T> actual;
  
      /** Holds the current subscription if any. */
      private final AtomicReference<Disposable> subscription = new AtomicReference<Disposable>();
  
      private QueueDisposable<T> qs;
  
      /**
       * Constructs a non-forwarding TestObserver.
       * @param <T> the value type received
       * @return the new TestObserver instance
       */
      public static <T> TestObserver<T> create() {
          return new TestObserver<T>();
      }
  
      /**
       * Constructs a forwarding TestObserver.
       * @param <T> the value type received
       * @param delegate the actual Observer to forward events to
       * @return the new TestObserver instance
       */
      public static <T> TestObserver<T> create(Observer<? super T> delegate) {
          return new TestObserver<T>(delegate);
      }
  
      /**
       * Constructs a non-forwarding TestObserver.
       */
      public TestObserver() {
          this(EmptyObserver.INSTANCE);
      }
  
      /**
       * Constructs a forwarding TestObserver.
       * @param actual the actual Observer to forward events to
       */
      public TestObserver(Observer<? super T> actual) {
          this.actual = actual;
      }
  
      @SuppressWarnings("unchecked")
      @Override
      public void onSubscribe(Disposable s) {
          lastThread = Thread.currentThread();
  
          if (s == null) {
              errors.add(new NullPointerException("onSubscribe received a null Subscription"));
              return;
          }
          if (!subscription.compareAndSet(null, s)) {
              s.dispose();
              if (subscription.get() != DisposableHelper.DISPOSED) {
                  errors.add(new IllegalStateException("onSubscribe received multiple subscriptions: " + s));
              }
              return;
          }
  
          if (initialFusionMode != 0) {
              if (s instanceof QueueDisposable) {
                  qs = (QueueDisposable<T>)s;
  
                  int m = qs.requestFusion(initialFusionMode);
                  establishedFusionMode = m;
  
                  if (m == QueueDisposable.SYNC) {
                      checkSubscriptionOnce = true;
                      lastThread = Thread.currentThread();
                      try {
                          T t;
                          while ((t = qs.poll()) != null) {
                              values.add(t);
                          }
                          completions++;
  
                          subscription.lazySet(DisposableHelper.DISPOSED);
                      } catch (Throwable ex) {
                          // Exceptions.throwIfFatal(e); TODO add fatal exceptions?
                          errors.add(ex);
                      }
                      return;
                  }
              }
          }
  
          actual.onSubscribe(s);
      }
  
      @Override
      public void onNext(T t) {
          if (!checkSubscriptionOnce) {
              checkSubscriptionOnce = true;
              if (subscription.get() == null) {
                  errors.add(new IllegalStateException("onSubscribe not called in proper order"));
              }
          }
  
          lastThread = Thread.currentThread();
  
          if (establishedFusionMode == QueueDisposable.ASYNC) {
              try {
                  while ((t = qs.poll()) != null) {
                      values.add(t);
                  }
              } catch (Throwable ex) {
                  // Exceptions.throwIfFatal(e); TODO add fatal exceptions?
                  errors.add(ex);
                  qs.dispose();
              }
              return;
          }
  
          values.add(t);
  
          if (t == null) {
              errors.add(new NullPointerException("onNext received a null value"));
          }
  
          actual.onNext(t);
      }
  
      @Override
      public void onError(Throwable t) {
          if (!checkSubscriptionOnce) {
              checkSubscriptionOnce = true;
              if (subscription.get() == null) {
                  errors.add(new IllegalStateException("onSubscribe not called in proper order"));
              }
          }
  
          try {
              lastThread = Thread.currentThread();
              if (t == null) {
                  errors.add(new NullPointerException("onError received a null Throwable"));
              } else {
                  errors.add(t);
              }
  
              actual.onError(t);
          } finally {
              done.countDown();
          }
      }
  
      @Override
      public void onComplete() {
          if (!checkSubscriptionOnce) {
              checkSubscriptionOnce = true;
              if (subscription.get() == null) {
                  errors.add(new IllegalStateException("onSubscribe not called in proper order"));
              }
          }
  
          try {
              lastThread = Thread.currentThread();
              completions++;
  
              actual.onComplete();
          } finally {
              done.countDown();
          }
      }
  
      /**
       * Returns true if this TestObserver has been cancelled.
       * @return true if this TestObserver has been cancelled
       */
      public final boolean isCancelled() {
          return isDisposed();
      }
  
      /**
       * Cancels the TestObserver (before or after the subscription happened).
       * <p>This operation is thread-safe.
       * <p>This method is provided as a convenience when converting Flowable tests that cancel.
       */
      public final void cancel() {
          dispose();
      }
  
      @Override
      public final void dispose() {
          DisposableHelper.dispose(subscription);
      }
  
      @Override
      public final boolean isDisposed() {
          return DisposableHelper.isDisposed(subscription.get());
      }
  
      // state retrieval methods
      /**
       * Returns true if this TestObserver received a subscription.
       * @return true if this TestObserver received a subscription
       */
      public final boolean hasSubscription() {
          return subscription.get() != null;
      }
  
      /**
       * Assert that the onSubscribe method was called exactly once.
       * @return this;
       */
      @Override
      public final TestObserver<T> assertSubscribed() {
          if (subscription.get() == null) {
              throw fail("Not subscribed!");
          }
          return this;
      }
  
      /**
       * Assert that the onSubscribe method hasn't been called at all.
       * @return this;
       */
      @Override
      public final TestObserver<T> assertNotSubscribed() {
          if (subscription.get() != null) {
              throw fail("Subscribed!");
          } else
          if (!errors.isEmpty()) {
              throw fail("Not subscribed but errors found");
          }
          return this;
      }
  
      /**
       * Run a check consumer with this TestObserver instance.
       * @param check the check consumer to run
       * @return this
       */
      public final TestObserver<T> assertOf(Consumer<? super TestObserver<T>> check) {
          try {
              check.accept(this);
          } catch (Throwable ex) {
              throw ExceptionHelper.wrapOrThrow(ex);
          }
          return this;
      }
  
      /**
       * Sets the initial fusion mode if the upstream supports fusion.
       * <p>Package-private: avoid leaking the now internal fusion properties into the public API.
       * Use ObserverFusion to work with such tests.
       * @param mode the mode to establish, see the {@link QueueDisposable} constants
       * @return this
       */
      final TestObserver<T> setInitialFusionMode(int mode) {
          this.initialFusionMode = mode;
          return this;
      }
  
      /**
       * Asserts that the given fusion mode has been established
       * <p>Package-private: avoid leaking the now internal fusion properties into the public API.
       * Use ObserverFusion to work with such tests.
       * @param mode the expected mode
       * @return this
       */
      final TestObserver<T> assertFusionMode(int mode) {
          int m = establishedFusionMode;
          if (m != mode) {
              if (qs != null) {
                  throw new AssertionError("Fusion mode different. Expected: " + fusionModeToString(mode)
                  + ", actual: " + fusionModeToString(m));
              } else {
                  throw fail("Upstream is not fuseable");
              }
          }
          return this;
      }
  
      static String fusionModeToString(int mode) {
          switch (mode) {
          case QueueDisposable.NONE : return "NONE";
          case QueueDisposable.SYNC : return "SYNC";
          case QueueDisposable.ASYNC : return "ASYNC";
          default: return "Unknown(" + mode + ")";
          }
      }
  
      /**
       * Assert that the upstream is a fuseable source.
       * <p>Package-private: avoid leaking the now internal fusion properties into the public API.
       * Use ObserverFusion to work with such tests.
       * @return this
       */
      final TestObserver<T> assertFuseable() {
          if (qs == null) {
              throw new AssertionError("Upstream is not fuseable.");
          }
          return this;
      }
  
      /**
       * Assert that the upstream is not a fuseable source.
       * <p>Package-private: avoid leaking the now internal fusion properties into the public API.
       * Use ObserverFusion to work with such tests.
       * @return this
       */
      final TestObserver<T> assertNotFuseable() {
          if (qs != null) {
              throw new AssertionError("Upstream is fuseable.");
          }
          return this;
      }
  
      @Override
      public void onSuccess(T value) {
          onNext(value);
          onComplete();
      }
  
      /**
       * An observer that ignores all events and does not report errors.
       */
      enum EmptyObserver implements Observer<Object> {
          INSTANCE;
  
          @Override
          public void onSubscribe(Disposable d) {
          }
  
          @Override
          public void onNext(Object t) {
          }
  
          @Override
          public void onError(Throwable t) {
          }
  
          @Override
          public void onComplete() {
          }
      }
  }
  